The most common interventional procedure in the field of Pulmonary Medicine (i.e., medicine pertaining to the respiratory system) is bronchoscopy, in which a bronchoscope is inserted into the airways through the patient's nose or mouth. The structure of a bronchoscope generally includes a long, thin, flexible tube that typically contains three elements: an illumination assembly for illuminating the region distal to the bronchoscope's tip via an optical fiber connected to an external light source, an imaging assembly for delivering back a video image from the bronchoscope's distal tip, and a lumen or working channel through which instruments may be inserted, including but not limited to diagnostic (e.g., biopsy tools) and therapeutic (e.g., laser, cryo or RF tissue elimination probes) instruments. The distal tip of a bronchoscope is steerable and therefore rotating a lever placed at the handle of the bronchoscope actuates the steering mechanism by deflecting the tip in two opposite directions.
Bronchoscopes are limited, however, in how far they may be advanced through the airways due to their size. Typically, a bronchoscope is much wider than other types of catheters, mainly due to the size constraints placed on their design by the camera. Unfortunately, the lesion or target of interest is often located deeper in the lungs than a bronchoscope can travel. Hence, three-dimensional location technology has been developed that allow the navigation of a steerable catheter deep into the lungs. The catheter includes a sensor that can be detected magnetically with great precision. Of particular relevance to the present invention are the devices and methods described in the following references: PCT Patent Publication No. WO 03/086498 entitled “Endoscope Structure and Techniques for Navigation in a Branched Structure” to Gilboa; U.S. Pat. No. 7,233,820 entitled “Endoscope Structures And Techniques For Navigating To A Target In Branched Structure” to Gilboa; U.S. Pat. No. 6,947,788 entitled “Navigable Catheter” to Gilboa; U.S. Pat. No. 6,833,814 entitled “Intrabody Navigation System For Medical Applications” to Gilboa et al.; U.S. Pat. No. 6,711,429 entitled “System And Method For Determining The Location Of A Catheter During An Intra-Body Medical Procedure” to Gilboa et al.; U.S. Pat. No. 6,615,155 entitled “Object Tracking Using A Single Sensor Or A Pair Of Sensors” to Gilboa; U.S. Pat. No. 6,593,884 entitled “Intrabody Navigation System For Medical Applications” to Gilboa et al.; U.S. Pat. No. 6,380,732 entitled “Six-Degree Of Freedom Tracking System Having A Passive Transponder On The Object Being Tracked” to Gilboa; U.S. Pat. No. 6,188,355 entitled “Wireless Six-Degree-Of-Freedom Locator” to Gilboa; each of which is hereby incorporated by reference in its entirety.
These references describe methods and devices in which locatable guides (“LGs”), enveloped by sheaths, are used to navigate to a location within the lung. The guide/sheath combination is inserted into the lung via the working channel of a bronchoscope. Once the tip of the guide is located at its target, a lock, which is placed at the orifice (“connection port”) of the bronchoscope's working channel, is operated to prevent the sheath from sliding in or out of the bronchoscope. The guide is then withdrawn from the sheath, leaving the sheath in place to guide a tool to the required target location.
Once the target has been reached with the LG, the LG is removed, leaving the sheath in place as a conduit to the target for other tools. However, the present design includes most or all of the location technology on the LG. Hence, once the LG is removed from the sheath, the physician is assuming that the sheath remains in close proximity to, and pointed at, the target.